Interlocking system for railroads



Nov. 26, 1940. R, N EY INTERLQCKING SYSTEM FOR RAILROADS Filed June 29, 1958 9 Sheets-Sheet ATTORNEY Brio 65.2

Nov. 26, 1940. R. M. PHINNEY INTERLOCKING SYSTEM FOR RAILROADS 9' Sheets-Sheet 5 Filed June 29, 1958 TTORNEY BY 0 A Mario SE2 26, 1940. R. M. PHINNEY I INTERLOCKING SYSTEM FOR RAILROADS Filed June 29, 1938 9 Sheets-Sheet 4 INVENTOR 76. m. ATT NEY ZOEISIQ QWEE Nov. 26, 1940. R. M. PHINNEY INTERLOCKING SYSTEM FOR RAILROADS Filed June 29, 1938 9 Sheets-Sheet .5

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Nov. 26, 1940. R. M. PH INNEY INTERLOCKING SYSTEM FOR RAILROADS Filed June 29; 1938 9 Sheets-Sheet 6 7 m3: g i 52 a mHI I IHHHHHIIT U U illk z Nov. 26, 1940, R. M. PHINNEY INTERLOCKING SYSTEM FOR RAILROADS Filed June 29, 1938 9 Sheets-Sheet 7 INVENT mm P K P EL J Nov} 26, 1940. R. M. PHINNEY INTERLOCKING SYSTEM FOR RAILROADS' 9 Sheets-Sheet 8 Filed June 29, 1938 Nov. 26, v1940. R. M. PHINNEY 292231126 INT-ERLO CKING SYSTEM- FOR RAILROADS Filed June 29, 1938 9 Sheets-Sheet 9 mzoPSEE muEo fizou mum m drm P E Patented Nov. 26, 1940 UNITED STATES INTERLOCKING SYSTEM FOR RAILROADS Robert M. Phinney, Rochester, N. Y.-, assignor to General Railway Signal Company, Rochester,

Application June 29, 1938, Serial'No. 216,459 32 Claims. (01. 246-434) This invention relates to interlocking systems for railroads, and it more particularly pertains to an interlocking system of the entrance-exit type, which includes a coded communication system for communication between remotely located track layouts and a control office.

A system for governing trafiic through complex track layouts should be so simple in the manipulations required as to conserve a maximum amount of the operators time and effort for the planning of train movements and the general dispatching of trafiic. In an entrance-exit type of interlocking system, a miniature track diagram of the actual track layout is provided with control buttons and indicators in a manner to make a composite picture of operation and actual conditions. Control buttons are located on the miniature track diagram at points representative of the route ends, and indicators are provided to show the positions of switches, clear or stop conditions of signals, and the locations of trains. --In accordance with this invention only one self-restoring control push button, or the equivalent, is provided for each end of each route. It is to be understood, however, that other types of buttons and control switches can as well be used, and that a button can be provided for each entrance point and another button provided for each exit point, in accordance with the requirements of practice. A route, as referred to in this description, is to be considered as the right of way set up over the track switches between an entering signal and the next signal for governing traffic in the same direction, or to the limit'of the interlocking plant, if such second signal is not provided.

This invention provides that the defining of each route to be set up is accomplished by the joint but sequential operation of the buttons for 3m the opposite ends of that route. In order to determine the direction of traflic over each route,

the button for the entrance end to that route is operated first, and its operation is followed by the operation of the button for the exit end of 45 that route.

Such a defining of each route is transmitted by code, as provided by this invention, to a particular station in the field, over any suitable type of communication system, such, for example, as the coded communication system shown in the Judge et a1. Patent No. 2,082,544, dated June 1, 1937. Such a field station is considered'as including track switches and signals and their control apparatus, grouped at a particular location in the 55. fie1d 1 positions for that lever.

A code, which-is selected by the operation 01 individual switch control levers on the control panel, -for-'the auxiliary operation of a group of track switches, can also be transmittedfromj the control ofi'ice to the particular field station 'for which those levers are provided.

In order that the same codes can be usedin transmitting route controls 'as are used in trans v mitting auxiliary switch controls, for the same field station, distinctive control station codes are :0 provided for each field station. That is, the transmission of each route-control code for a particularstation is preceded by the transmission of a particular control station code, and the transmission 'of each auxiliary switchcontrol code 1 for that same field station is preceded by the transmission ot a dilferent control station code. Although only two control station codes are assigned to a particular field station in this embodiment of the present invention, it is to be 20 understood that the capacity of the system can be increased in accordance with the requirements of practice by dividing the route controls and the auxiliary switch controls tobe transmitted to a particular field station into groups, each group .25 being assigned a particular control station code. When-route controls are transmitted from the control office to a particularfield station, a composite code is transmitted consisting respectively 'of characters forming a control station code characters forming a route end code corresponding with the entrance point defined by the operatonand characters forming a route' end code corresponding with the exit point defined by the operator. J.

The circuits are so arranged that the transmission of a series of impulses in response to the defining of a route by the operation of buttons for both ends of that route, is rendered efiective automatically upon the operation of the button 40 for the exit end of that route. In order to start the transmission of a seriesof impulses for the auxiliary operation of a group of track switches, a start button is depressed, following the selection of the code to be transmitted by the operation of the auxiliary switch control levers for that group of track'switches; Although a separate start push button-has been shown in this embodiment of the present invention, it is to be understood that a start contact correspondingwith the start button conact could as well be provided on each of the auxiliary switch control levers as a contact to be closed if the lever is operated beyond the .regular normal or reverse 5 The setting up of routes for different stations which are not receiving codes, can be initiated by the operator during operation of the communication system, and the defining of those routes is stored until the communication system the operation of a cancel button.

To restore parts of the system, which are associated with a route, to normal, after-that route has been completely set up, the operator has only to depress the button twice for the entrance to that route. The second time the button is depressed a series of impulses, including a message for the restoration to normal of parts, of the system associated with that route, is applied to the line circuit at the control oflice, provided the line circuit is not being used. If the line circuit is in use during such operation, the message is stored until the line circuit is available for its transmission. 1

.The self-selecting network provided by this in,- vention for each of the field stations is an improvement over the self-selecting network shown in the application of Phinney and Hitchcock Ser. No. 183,272, filed January4, 1938.

Means is provided for transmitting indica .tions from each field station to the control office. When indicating the setting up of a route, as provided by this invention, the transmission of indications, in accordance with changes in the position of the track switches, is delayed until the signal for that route is cleared. Thus the condition of an entire route is. transmitted on one indication cycle. When indicating the position of track switches positioned in'accordance with the transmission of auxiliary switch control codes, however, the transmission of indications is initiated as soon as the track switcheshave completed their operation. 7

An object of this invention is to provide the above simplified mode of operation for an operator at the control ofiice, by which the track layouts remotely located from that ofiice can be efliciently controlled.

Another object of this invention. is to consolidate a number of remotely located interlocking 1 plants into a network of interlocking plants controlled from a single control office, thus centralizing the control of various units of a railway signalling system.

A still further object of the present invention is to include in onemessage, or cycle of operation, all of the control codes necessary for completely setting up a route at the field station for which those controls are selected, irrespective of the number of track switches included in that route.

Qther objects, purposes and characteristic features of the present invention willbe in part obvious from the accompanying drawings, and in part pointed out as the description of the invention progresses.

In describing the invention in detail,- reference is. made to the accompanying drawings, in which tive exponents representative of their location or by reason of preceding numerals, and in which:

Figs. 1A and 13, when placed side by side,

illustrate the means provided. forsetting up coded messages, in accordance with the manipulation of the control buttons and levers on the panel of the control machine; Fig. 2 illustrates the means provided at the control office for the stepping, impulsing of theline circuit, and the reception of indications; Fig. 3 illustrates the means provided at oneof the field stations for receiving codes transmitted from the control office, and also illustrates means provided at the field station for transmitting indications to the control ofiice;

Fig. 4 illustrates means provided at one of the fieldstations for execution of the messages received from the control ofiice;

Fig. 5 illustrates the self-selecting network provided at oneof the field stations for setting up routes through the track layout with which it is associated, in accordance with codesreceived from the control office; 1

Fig. 6 illustrates certain typical circuits relative to the switch and signal controls at the various field stations; 1

Fig. 7 illustrates the means provided by this invention for transmitting indications from a field station to the control office, and also illustrates a means provided for delaying the transmission of such indications, under certain conditions, until a route is completely setup; and

Fig. 8 illustrates a means which is provided by this invention for indicating, on the control panel in the control ofiice, various conditions at the field stations.

In order to simplify the description, reference is made from time to time to functionscommon to all parts of a similar characterby use of the 'the invention have been shown diagrammatically and certain conventional illustrations have been employed, the drawings having been made more -Wlth the purpose, of facilitating the disclosure as to the principles and mode of operation, than with the idea of illustrating the specific construction and arrangement of parts that would be employed in practice. Thus the various relays and their contacts are illustrated in a conventional manner, and symbols are used to indicate connections to terminals of batteries or other sources of electric current, instead of showing all of the wiring connections to thoseterminals.

Various relays are shown on different pages of the drawings. in block form only, and some parts of the system have been illustrated onmore than one page, in order that various features of the system can be more clearly illustrated.

The symbols (-1-) and are employed to indicate the positive and negative terminals respectively of suitable batteries or other sources of direct current; and the. circuits with which I those symbols are used always have. current flowing in the same direction. The symbols (3+) and (B') indicate connections to the opposite terminals of a suitable battery or other direct currentsource which has a central or intermediate tap designated (CN); and. the circuits with which these symbols are used can have current flowing in one direction or the. other, depending upon the particular terminal used in combina tion with the intermediate tap' (CN). When alternating current is used in place of direct current, the particular symbols employed represent the relative instantaneous polarities.

APPARATUS Track Zayout.With reference to Figs. 1A, 1B and Fig. 5 of the accompanying drawings, the track layout has been illustrated as having been made up of a stretch of double track, the two tracks of which have been connected at various points by crossovers Zts, 3ts and lts.

Signals l and H (see Fig. areprovided for governing east bound traffic, and signals l2 and [3 are provided for governing west bound trafilc. Those signals, together with other apparatus for the track layout for which they are provided,

constitute a field station. Although the signals are not shown for governing traiiic over crossover 4ts (see Fig. 1B) it is to be understood that such signals are provided, and that those signals, together with other apparatus for the track layout for which they are provided, constitute another field station. In order to simplify the disclosure of this invention, various parts of the system relative to the field stations are shown only in a typical form for a particular one of the stations.

The crossovers ts are provided with switch machines SM for causing the operation of their associated track switches to normal or reverse positions. The switch machines 2SM and 3SM have been shown as being associated with crossovers 2ts and 3ts respectively. The switch machines may be of any suitable type such, for example, as the type disclosed in the patent to W. K. Howe, Patent No. 1,466,903, dated September 4, 1923. In order to simplify the disclosure only one switch machine SM has been show associated with each crossover, but it is to be understood that separate switch machines can be provided for each end of each crossover in accordance with the requirements of practice. The motors for the switch machines can be controlled, for example, as shown in the patent to W. H. Hoppe et al., Patent No. 1,877,876, dated September 20, 1932. If they are controlled in this manner, the relay CR of that patent is controlled by relay WZ of the present disclosure.

The signals II], II, I2 and I3 (see Fig. are of the search light type, havingchecking contacts associated therewith, as shown, for example, in the patent to O. S. Field, Patent No. 1,835,150, dated December 12, 1931. The signal indications have been assumed as providing a green light for a clear indication and a red light for a stop indication, and it is to be understood that a yellow light can be provided for a caution indication if such an indication is required in practice. It is also to be understood that other types of signals can as well be used, such as the semaphore type, color light signals having individual lamp units, or any other suitable type of signals, all within the scope of the present invention.

Track circuits are provided in the usual manner for the various track layouts included in the system, such, for example, as for the track sections 5, 6 and 1 (see Fig. 6) which have been shown as having track relays 5T, ET and 'IT associated therewith. Although the track batteries and other details of the track circuits are not shown, it is to be understood that they are provided in the usual manner.

A switch point detector relay WP is provided for each crossover, relays ZWP and 3WP. having been shown. Each of the relays WP is of the polar neutral type and is energized with one polarity or the other in accordance with the normal or reverse locked position of the track switches for the associated crossover and the corresponding position of the switch machine SM, and it is deenergized Whenever the switch points and/or the operating mechanism of the switch machine are unlocked. The circuit for causing such an operation of the relay WP is governed throughthe medium of a point detector contact,

mechanism as shown, for example, in the patent to C. S. Bushnell, Patent No. 1,517,236, filed November 25, 1924.

Control machine.-The control machine may be of any suitable type of construction, such, for example, as that shown in the application of J. F. Merkel, Ser. No. 169,436, filed October 16, 1937, in which the machine is made up of sections provided for various stations included in the system. A master unit is provided which consists of various parts of the system which are common to the sections for each of the field stations. The other sections of the machine can be provided as one section for each station, or various stations can be included in one section, according to the requirements of practice. Such an arrangement provides that changes and replacements can be made for parts of the control machine without materially interfering with the operation of other parts.

A control panel is provided on the front of the sections, which has constructed thereon a miniature track diagram similar to the track layout in the field for which that section of the machine is provided. Various indicator lamps are provided on the miniature track diagram at positions to indicate various conditions at the field stations.

A self-restoring push button B, having an operating contact closed when the button is depressed, is provided on the miniature track diagram at each point representative of a route end in the track layout with which that diagram is associated. The buttons B can include indicator lamps, as shown in Fig. 8, or the indicator lamps can be provided on the track diagram separate from the buttons, in accordance with the requirements of practice. Buttons 10B, HB, I2B, 13B, MB, I5B, IBB and NB have been illustrated (see Figs. 1A and 1B) as having been associated with the miniature track diagram in such a manner that it is obvious with which route ends they are associated from their position on the track diagram. 1

Auxiliary switch control levers are pro-vided on the control panel for the auxiliary operation of the track switches for each of the crossovers included in the various track layouts, of which levers ZSML, SSML and 4SML have been shown.

Code determining relays-The series of impulses applied to the line circuit during a cycle of operation for the communication of controls, is made up of several codes for performing various functions. As a means for selecting such codes various code determining relays are provided.

The relays CD (see Figs. 1A and 1B) are provided for rendering codes effective for transmission to only one particular field station at one time, each relay CD having associated'therewith code jumpers which select a code of impulses to which only one particular field station is responslve.

to each route, and the picking up of that relay determines a code to be transmitted to a particular field station for defining that entrance point at that station. Relays IDNR, HNR, iZNR and ISNR have been shown as having been provided for the entrance points at signals 10, I l, l2and l3 respectively.

In somewhat of a similar manner relays IUXR, HXR, IZXR and I3XR. are provided to select a code for transmission to a particular fieldstation for the definingof exit points at signals IO, M, I2 and I3 respectively.

A control station relay SR (see Fig. 1A.) is provided at the control oflice for selecting the control station code for transmission to the particular field station illustrated in detail. If that SR relay is picked up during the transmission of controls to that field station, a control station code identifying .the control code as representative of auxiliary switch controls is selected, and if that relay is dropped away during the transmission of controls to that field station a control station code identifying the. control code as representative of defined route ends is selected.

Relay NCI-I is provided in order to select the operation of a second button in setting up-a route as being provided for defining the exit point for that route, and its associate relay NCHS provides that the depressing of a button for an entrance point will not energize the relay XR associated with that button for an exit point.

The change relay CH starts the communication system into operation, after the various control codes to be transmitted have been selected.

The change relays CH have associated therewith a manually operable self-restoring cancel button CNIB. Suitable relays relative to the communication system are provided at the control ofiice, such as relays CHP, CDS, C, FC, NC, PC, E, EP, F, FP, ZFP, SA, ZSA, DV, MF, MB, VP, IV, 2V, 3V, 4V, 5V, 6V, IV and LV. The function and characteristics of all of these relays has been shown in the above mentioned Judge et al. patent, No. 2,082,544. For convenience in referring to relays performing similar functions in that patent as those shown for this invention, the reference characters used in the drawings for this disclosure have been made to correspond with the reference characters for similar parts shown in that patent.

\ The relays IV, 2V, 3V, 4V, 5V, 6V, 1V and LV together with halfstep relay VP, form a stepping relay bank which is responsive to the impulsing of a line circuit extending from the control oflice to the various field stations. Such impulsing is efi'ected by impulsing relays E and EP.

Relay F at the control ofilce is a quick acting biased-to-neutral polarized relay and it has associated therewith quick acting neutral repeater relays FF and ZFP. Rel'ays SA and ZSA are slow in dropping away, which provides that after they are picked up at the beginning of the transmiss'ion' of a series of impulses, they remain picked up throughout that cycle of operation.

Relays PB, PF, ST, GK, TK, (ANK, BN'K, RK, WRK, WNX, NXS and FL (see Fig. 8) are used at the control ofiice in'registerlng indications received from the field stations.

Suitable relays relative to the'communication' The relays IV 2V 3V 4V 5V GVlf'lV and LV together with halfx-step'relay VP forni'a stepping relay bank at the field station illustrated that is responsive. to the impulsing of the line A change relay CH (see also Fig. 7) is pro-- vided at the field station illustrated in Fig. 3 for the purpose of initiating the transmission-of indications front that field. station to the control office, and relays L0 PB and PF have been provided for purposes'---rlative to the transmission of those indications.

selecting co'de transmitted from- The relays NR XR1, CAR, AN,,BN, R and WS I (see Fig. 4) are responsiveat the: end of an operating cycle, to the positioning of the code receiving relays PS and NS, and the selective energization of those relays determines the route to be set up at that field station, or the track switches to be positioned in accordance with the positioning of the auxiliary switch control levers for those track switches at the control oflice. 1 I

Relay NR 're'gisters the entrance point for the route selected,-re1ay'XR registers the exit point for the route selected, and relay CAR, when energized, causes the restorationto normal of a route having an entrance; point with'which that relay is associated. Therelays AN, BN and R cause the normal or reverse positioning of the track switches for the crossover with which those relays are associated. Relay WS, when energized, allows each change in the position of the track switches to initiate an indication cycle.

A relay WZ (see Fig. 6), associated with each crossover, is responsive to the picking up-of the AN, BN or R relays ifor that crossover, and the picking up of relay WZ causes the application 'of positive ornegative-energy' to the switch machine SM with whieh'it is associated, in accordance with the normal or reverse switch control relays energized. A contact of a lock relay L is included in'the circuit of relay WZ in order to allow the operation of the switchrnachine only under conditions when such operation is safe.

A relay NCR and a relay RCR (see Fig. 6) is provided for each crossover for repeating the position of. the track switches for that crossover in correspondence with the picked up position of the switch control relays AN, BN or R, and

relays NOR and RCR close a circuit for the entering signal to each route which is set up, thus causing the signal to be cleared only after each of the track switches in the route has completed its operation.

A normally energized relay M (see Fig. 6) is provided for repeating the stop position of each of the signals, the circuit for relay HIM having been shown associated with signal ID as being typical of the circuit for the other relays M provided for the other signals.

An approachlocking relay ALS is associated with each signal, and it is-provided with a thermal relay THR, for delaying the picking up'of that relay under certain conditions. It is to be understood that modifications of the approach locking can be provided in accordance with the requirements of practice; ..For' example,- in some OPERATION In considering the details. of the operation'of the system, little reference is made to the details relative to the communication part of the system, because such details can be obtained by referringto the above mentioned Judge et al.

patent, No. 2,082,544. In order to make clear how the description in that Judge et a1. patent is applied to the present invention, corresponding relays are shown in this disclosure as having corresponding reference characters. Consideration is given, however, to the mode of operation of the communication system in a general way which should be sumcient for an understanding of the present invention by those familiar with the art. a

Communication system genemZ.-The communication system provides that control codes made up of time spaced positive and negative impulses are applied at the control ofiice to a line circuit having a control line wire 20 (see Fig. 2), which includes, in series, the winding of a three-position polar neutral relay F at the control oflice and at each of the field stations. At the most distant station from the control oflice the control line wire 20 is connected to a return line wire 2|.

A series of impulses impressed upon the line circuit, having polarities selected in a manner hereinafter described, causes the relay F at all stations to operate in synchronism and thus causes the operation of the stepping relay banks with which those relays F are associated.

When reference is made from time'to timeto the positive or negative energization of the line circuit, such reference refers to the connecting of the positive or negative terminal respectively to the side of-the line circuit including control line wire 20.

The first impulse of a seriesapplied to the line circuit is used for conditioningapparatus in the control office at each station for a cycle of operation. During the first time space in a series, conveniently 0311813..11118 first off period, the first of the stepping relays is picked up,-and in a similar manner a successive stepping relay is picked up during each of the following off periods.

The stepping at each of the field stations is rendered effective during the transmission of the station selecting code only so long as that code, which is the first group ofimpulses of a series, corresponds with the position of :code jumpers, step-by-step, at that station. Thus it is obvious that the series'of impulses carries a message which, through the process of elimination, maintains only one particular station in communication with the control ofiice for the reception of the remainder of the impulses of that series.

After the station selecting code is completed, various control codes are transmitted to the station which remains in communication with the control office after the stepping at all of the other stations has stopped. The period'of de- -energization of the line circuit at the en'd'of the last impulse of a series, which is conveniently called the clearing out period, provides for the restoration of the communication system to noron periods.

mal at rest conditions.

An indication line circuit consisting of line wires 22 and 23 .(see Fig. 2)., is opened or closed,

at a field station which is transmitting indica tions, during each step. .Such opener or closed condition registers in the control ofli'ce, the condition of apparatus at the field station which causes such an opened or closed condition. Relay PB (see Fig. 3) is used in closingthe indication:line circuit duringthe off period, and relay PF is used in closing the indication line circuit during the energization of the line-circuit following the off periods, conveniently called Relays MB and MF (see Fig. 2) at the control office respondto the closing of the line circuit during off and on periods respectively. The stepping is effected during an indication cycle, by the transmission o-f'a phantom code from the control office over the line circuit, which causes the operation ofthe stepping at the field stations, but which renders impulses ineffective for transmitting controls; In other words, a phantom code does not contain code elements corresponding with any station selecting code used.

The station transmitting indications is reg-v istered at the'control ofiice by means of a registration code, during the beginningof the indication cycle, which is predetermined by jumpers at the sending field station which determine the opened or closed condition of the indication line circuit step-by-step.

The communication system can be operative for the transmission of controls and for the transmission of indications onseparate cycles of operation, or both transmitting means can be efiective at the same time. Such simultaneous operation is called duplex operation, and is explained in detail in the above mentioned Judge et a1. patent. During such operation a station not selected for the reception of controls can transmit indications, and the stepping at that station is efiected by the impulses-being applied to the line circuit at the control ofiice for the transmission of controls, rather than by the transmission of a phantom code.

Normal conditions.--'With reference to Figs. 1A, 1B and 2, it wil1 be noted that, during a'period of rest,.all of the relays associated with the system at the control office are deenergized, and that both .of the relays NC and PC, in a dropped away position, cause the opening of the line circuit extending to the field stations. Likewise, with reference. to Fig. 3, it will be noted that each of the relays at the field stations relative to the communication system are in a dropped away position, with the exceptionof the change relay CH With reference to Fig. 5, the signals for the track layout illustrated; have been shown as being normally at stop with their red lamps illuminated, which position causes the energization of the signal at stop repeater relay M, as is locking relay IOALS, which, is associatedwwith signal l0, energized from through a circuit including front contact 25 of relay 10M, winding of reIayJBTHR, front contactZS of relay l-cAL's, and winding .ofurelay terms; to .An

approach locking relay ALS hasbeen shown associated with each signal and hasa control circuit (not shown) provided inthe same manner as has been described. for relay IBALS.

, vIt is assumedthat thetrackrlayoutsareunoccupied, during normal conditionsiwhich would cause the energization of thetrack circuits for all of the track relays, and cause the track relays ST and T (Fig. 5) and their associated; repeater relays, to be in their. pickedup position. It is also: to .be'understood that under the normal conditions the approach tracksections are unoccupied, as shown by the picked up position, for example, of relay lT-(see Fig. 6)..

Undernormal conditions, when the approach locking rela s and the relays for thedetector track sections. are-picked up, the lock relay for each of the track switches with which those relays are associated is energized :as is typically shown, for example, in the stick circuit for relay 2L (see Fig. ;'6) which is closed from ,through acircuit includingfront contact s a-or relay. 2L, back contact 3.4 vof relay.12RC1'1.,'back contact 33 of relay 2NCR,,Winding of relay 2L, front contact v32 of relay 5T, front contact 3|; of relay WALS, w

front contact .30 'of relay 6T,'front contact 29 of relay llALS, front. contact 28 of relay IZALS, and front contact Z'IofreIay iBALS,to'.(l.. i

Changerelay CH ..(see Fig. .7) is -maintained, under normalconditions, in a'picked up position by a stick circuit closedfrom through a circuit including back contact 35: of relay. ItXR, back contact tflnof .relay I ZXR, front contact. 38 of. relay IZM, front contact 39.-of relay l3M, front Contact 4810f relay 3W.P,front contact li of re.-

lay 2WP, front contact 42 of relay?- ST, front-contact 43 of relay 51, front contact 44 of relay HM,

front contact 45 of relay lilM, back contact 46 of relayil 15m, back Contact. of relay. ltXR;:front contact 4.3 of relay CI-Ikand upper winding of relay. CH to.() 1 r ,1 1 5' The. relays associated with the self-selecting networkprovided for each of the'track layouts in'the field arev dropped away during normal con ditions, as-is typically shown, for example, in

" Fig.5.

tion is' illuminated, and remains illuminated until, those controls arextrans'mitted. The. illumination of a lamp CHE 'indicates'to the operator thatcontrols for that station are store'd'or; are being transmitted, and that he should'vwait until 65 the lamp is extinguished before attempting ,to

initiate ,thetransmission of new controls for that station. It is. to be, understood that indicator lamps are associated with each route initiated for clearly indicating that route tov the operator inorder that he will not attempt to, set up conflictingrouts, although'the circuits are: so interlooked, that conflicting :routesfcannot' be contemporaneously set up.

-After; the operatorhas'lchecked the route,in. dic'atorlamps for a particulanstation to see. that there are noroutes'set up which conflict the route he is about to initiataandafterhe has checked the indication. of the lamp-CHE for that station to determine that all prior initiated COXl-r trols have been transmitted, he can proceed to initiate the setting up ofa route, for example,

- from signal ill to signal !2.

In setting up a route from signal Ii) to signal I2,Qthe. operator first depresses the button lllB for the entrance end of that route and'iith'en,

after having allowed that buttonto be restored, he, depresses the button 12B for the exit end of that route. Thei depression of thebutton- 12B causes the automatic start of thetransmission of control codes selected in response: to the joint operation of the buttons for both ends'of the route.

The depression of button HUB, under such conditions, causes the energiz'ation' of the lower Wind ing of an entrance relay lllNR-in series with'the winding of an entrance change stickrelay NCHS. Such a circuit is'closed from through a circuit including contact 49 of button lllB in a depressed position, lower'winding of relay lONR, back contact 50 of relay NCH, winding of relay NCHS, and back contact.5| of relay CH, to Thepicking up of relay IUNR closes a stick cir cuit for that relayfrom' through a circuit including contact 52 of. cancel'button CNB in a normal position, back contact 53 of relay CD, winding of relay NCH, front contact 54 of relay IDNR, and upper winding of relay lilNR, to

- The picking upof relay NCHS closes a stick circuit including front contact 55 of that relay for shunting contact 50"of relay. NCI-I out of the circuit. Relay NCHS remains. in a picked up position so long asthe entrance button which has been depressed isheld in a depressed position, and the picking up of that relay opens the circuit for the relays associated with the exit points of the routes in order to preventthef energizationofthe exit relay IDXR which is also associated with the buttonfor the. end of the 'route'at signal I0:

., When the operator allows the button IOB to be restored to its normal position, after relays liINR and NCI-I have been picked up, the circuit for relay NCHS is opened at contact 49 of button 1B in a depressed position, which causes that relay to drop away. i

. The operator now proceeds toi dfine-the exit end for the route which he. is' setting up from signal l0, to signal |.f2,-by the depression of button -l2B,. which closes a circuit for energizing the lower winding of relay l-ZXR from through a circuit including contact 56 of button IZB in a depressed position, back contact 57 of-relay l 3NR,

lower winding of relay I2XR, front contact 58 of relay NCH, back contact'59 of relay NCHS, and back contact-.60 of relay CH, to(). The picking up of relay IZXR cl'o'ses'a stick circuit for that relay from through a circuit including contact ,52of buttonCNB in anormalwposition, back contact 53 of relay CD, winding'of relay CH,

front contact 6,! of relay 12KB, and upper wind- When relay CH picks up, due to. its'energization by the above circuit, it closes a circuit for energizing its repeater relay CHIP,- from, through a circuit including back contact 620i relay- SA, back contact 63 of relay FC, upperwinding of relay CHIP, wire l ll, and front contact 64 of re,- lay CH, to Thepicking up of; relay CHE closes a t k circuit orrt att e ar om;

through a circuit including back contact 65 0frelay LV front contact 66 0f relay CI-IP, and

lower winding of relay CHP, to Energy is also applied to that stick circuit by back contact II8. of relay EP in order to maintain relay CHIP picked up until the end of the last of a series of impulses.

The picking up of relay CHP closes a circuit f energizing relay C from through a circuit including back contact 61 of relay SA, front contact 68 of relay CHP, and winding of relay C, .130

The picking up of relay C closes a stick circuit for that relay from through a circuitincluding back contact I3I of relay ZSA, front contact I32 of relay C, and winding of relay C, to At the start of the cycle, the relay SA picks up and applies energy to that stick circuit at front contact 61 before that stick circuit is opened by the picking up of relay 2SA, which follows the picking up of relay SA; wherebythat stick circuit is maintained closed throughout the cycle of operation. At the end of the cycle, however, relay SA drops away prior to the dropping away of relay ZSA, and effects the momentary opening of the stick circuit to cause the dropping away of relay C.

As soon as relay CH is picked up, the indicator lamp CHE is illuminated when an obvious circuit is closed at front contact I91 of relay CH, thus providing an indication that the stored controls for that station must be transmitted before initiating the transmission of other controls for that station.

A circuit is closed for energizing the lower winding of relay CD, from through a circuit including back contact 65 of relay LV, back contact 69 of relay 2SA, front contact I0 of relay C, back contact II of relay CDS, back contact I2 of relay2CH, wire II 9, front contact I3 of relay CH, lower winding of relay CD, and contact 14 of cancel button CNB in the normal position, to

The picking up of relay CD closes a stick circuit for that relay, which is also an energizing circuit for relay CDS, from through a circuit including front contact I5 of relay CHIP, winding of relay CDS, wire I20, front contact I5 of relay CD, upper winding of relayCD and contact I4 of button CNB in the normal position, to Energy is applied to that circuit by back contact I9 of relay EP to insure the energization of the circuit until the end of the last impulse of the series.

The picking up of relay CD closes a second energizing circuit for relay CH from through a circuit including back contact I33 of relay LV, wire I34, front of make-before-break contact 53 of relay CD, winding of relay CH, front contact 6| of relay IZXR, and upper winding of relay IZXR, to Make-before-break contact 53 provides that relays CH, IIJNR, NCH and IZXR are maintained energized during the picking up of relay CD. Part of that circuit is also common to the circuit for relays NCH and IUNR which is closed after relay CD picks up, from through a circuit including back contact I33 of relay LV, ,wire I34, front of make-before-break contact 53, winding of relay NCH, front contact 54 of relay EGN'R, and upper winding of relay IBNR, to Such circuits for relays CH, NCH, IUNR and .I2XR are maintained energized throughout the cycle of operation by reason of back contact I33 of relay LV, and energy is also applied to those circuits at back contact I35 of relay EP to insure that those relays remain energized until the end of the last impulse of the series.

above mode of operation, for the start of the transmission of controls relative to the route initiated, by means of the communication system.

Auxiliary means is provided for initiating the positioning of the track switches in order to allow the operator to set up routes through the interlocking plant which are not provided by the selfselecting network, and in order to allow the operator to set up routes through the interlocking plant if the self-selecting network fails to operate. Such auxiliary means for controlling the track switches also provides a means whereby the operator can cause the operation of a particular track switch, or a group of track switches, in order to free the switch points of obstructions, such, for example, as snow and ice.

Assume, for example, that the operator wishes to set up a route, not provided by the self-selecting network, from signal Ill to signal I2 via crossovers 2ts and 3158.

In order to initiate the proper positioning of the track switches for such a route, the operator first checks his indicator lamps as mentioned above, and then proceeds to operate the auxiliary levers 2SML and 3SIVLL to a reverse operating position, which has been assumed as'being to a downward position. He then depresses the send button SB for that station.

Such operation of the send 'button'SB closes a circuit for energizing a control station relay SR from through a circuit including contact ll of button SB in a depressed position, upper winding of relay SR, back contact 58' of relay NCH, back contact 59 of relay NCHS, and back contact Gil of relay CH, to The picking up of relay SR closes a stick circuit for that relay, which includes an energizing circuit for relay CH, from through a circuit including contact 52 of button CNB in a normal position, back contact 53 of relay CD, winding of relay CH, front contact I8 of relay SR, and lower winding of relay SR, to

The picking up of relay CH, due to its energization in the stick circuit for relay SR, causes the energization of :the relays CHP, C, ODS and CD in the same manner as has been heretofore described, and relay CE is maintained picked up until the end of the control cycle.

In order to initiate the transmission of a message for putting a signal to stop, the operator has only to depress the button twice for the route end with which that signal is associated. The first time the button is depressed, the relay NR for the entrance pointat that signal is picked up, and the second time that same button is depressed the relay XR. for the exit point at that signal is picked up. The picking up of the relay XR initiates the control cycle in the same manner as was described in detail for the initiation of the system for transmitting route end controls.

In considering an example of the above mentioned mode of operation for putting asignal to stop, assume the operator to initiate the putting of signal I0 to stop. Upon depressing button IilB the first time, relays IONR, NCI-IS and NCH are picked up in the same manner and including the same circuits as was heretofore described. After the button IBB is restored, relay NCHS is dropped away, due to its circuit having been opened at contact 49 of button IUB. The operator then depresses the same button a second time, and a circuit is closed for energizing relay IUXR from through a circuit including contact 80 of button IIlB in a depressed position, back contact 8I of relay IIN'R, lower winding of relay IEEXR, front contact 58 of relay NCH, back contact 59 of relay NCHS, and back contact 68 of relay CH, to It will be noted that relay NCHS does not pick up, upon depressing the button NB the second time, because its pick up circuit is held open at back contact Sill of relay NCH. The picking up of relay IBXR. closes a stick circuit for that relay, which includes the winding 7 of relay CH, from through a circuit includ lo" tion, back contact 53 of relay CD, winding of ing contact 52 of button CNB in a normal posirelay CH, front contact 82 of relay IIJXR, and upper winding of relay IllXR, to The picking up of relay CI-I causes the start of a control cycle in the same manner as has heretofore been described.

Having described various conditions relative to the mode of operation of the system for specific conditions of operation on the part of the operator it is to be understood that such operation is considered as typical for other similar specific conditions relative to the setting up of other routes, relative to the auxiliary operation of track switches to other positions, and relative to the putting of other signals to stop.

The above described circuits include certain interlock features. Whenever a button is depressed a. first time, for an entrance point, relay NCHS is maintained in a picked up position to open the circuit for the exit relay associated with that button at back contact 59. The picking up of relay NCH prevents the picking up of the control station relay SR, until the initiated route control has been transmitted or cancelled, by opening the pick up circuit for that relay at back contact '58. The picking up of relay CI-I opens the pick up circuit for the relays NR and KR atback contacts I and 60 respectively, and the opening of back contact 6!! also opens the pick up circuit for relay SR. Thus the code to be transmitted cannot be changed after a control cycle has been intiated. The inclusion of back contact 51 of relay I3NR in the pick up circuit for relay IZXR'prevents the initiation of an impossible route from' signal I3 to signal I2.

In a similar manner, control cycles for each of the stations can be initiated, for example, the operation of buttons for entrance and exit points for the track layout illustrated by the miniature track diagram shown in Fig. 13 causes the energization of the relay ZCH, which causes the start of a cycle in the same manner as described above as being responsive to the energization of relay CH. It is of course to be understood that control cycles for each of the field stations can be initiated by the start button associated with that field station, together with the positioning of the auxiliary switch control levers. v I

If starts for two or more stations are effecte simultaneously or at times prior to the dropping away of relay CDS, the front contact of the relay CH which is included in the pick up circuit of the relay CD associated therewith, and which is nearest the source of energy for the picking up of the relays CD, locks out all other relays CD for starts which have been initiated. For example, if relays CH and 20H become energized contemporaneously, while relay CBS is picked up, the picking up of relay ZCH opens the circuit for relay CD at back contact I2 and closes the circuit for relay 2CD at front contact 12. Thus 7 relay 2CD is given superiority over relay CD, due

to its position in the circuit. The opening of the circuit for the relays CD throughout a control. cycle at front contact II of relay CDS prestations.

vents the picking up of relays CD during a cycle, suchas preventing the energization of relay 2CD when a cycle has been initiated by relay CD.

It is therefore obvious that a start can be stored for each station by the energization of the relay CH for that station, and that the order in which those stored starts are transmitted is determined by the orderof the location of the relays CD for those I starts in their common control circuit.

Polarity selection of stepping impulses-The polarity of the first group of impulses of a series during a control cycle is selected in accordance with the position of various code jumpers and in accordance with the picked up or dropped away position of the control station relay SR. That first group of impulses defines the field station for which the controls are intended, and also defines the particular nature of the controls to be transmitted during that cycle of operation. That is, it defines, in this particular embodiment of the present invention, whether the controls to be transmitted during that cycle are for the designation of route ends, or whether the controls to be transmitted during that cycle are for the auxiliary positioning of a group of track switches. The first three impulses of that group are determined by the position of the code jumpers in a manner described in detail in the above menis dependent upon the number of field stations included inthe'system, and the number of control station codes required for each of those field The maximum number of different codes that can be provided by a particular number of impulses is equal to two raised to the power of the number of impulses. One of the codes is usually reserved, as in the present system, for the stepping during an indication cycle, and it is conveniently called a phantomcode.

To consider an example of how the station codes are selected, consider the system to have been initiated for the transmission of controls to the field station illustrated in Fig. 3. The

picking up of relay C (see Figs. 1A and 1B) due to such initiation, closes a'circuit for the energization of relay PC from through a circuit including front contact 83 of relay Cfback contacts 84, 85, 86, 81, 88-, I36 and I3! of relays IV; 6V, 5V, 4V, 3V, 2V and IV respectively, wire I-2I, front contact I38 of relay CD, jumper I39, wire I29, and winding of relay PC, to-

After the line circuit is deenergized by the picking up of the impulsing relay EP, (see Fig. 2) in a manner to be described in detail later, the first of the stepping relays IV is picked up and the above described circuit for relay PC is opened at back contact I31 ofrelay IV, A sec.- ond energizing circuit is closed however, for that relay PC from through a circuit including front contact 83 of relay C, back contacts 84, 85, 86, 81, 88 and I36 of relays IV, 6V, 5V, 4V, 3V and 2V respectively, front contact I31 of relay IV, wire I22; front contact I40 of relay CD, jumper I'4I, wire I29, and winding of relay PC, to

With relay PC picked up, the line circuit is energized fora second impulse which is of a positive polarity, as soon the impulsing relay EP is dropped away toclose that line circuit. After relay EP has again picked up to mark the end of the second impulse, relay 2V is caused to pick vention, define the route end which is used as drop away. A circuit is closed for the energize.- tion of relay NC by the picking up of relay 2V, from througha circuit including front contact 83 of relay C, back contacts 84, 85, 86, 8'1 and 88 of relays IV, 6V, 5V, 4V and 3V respectively, front contact I36 of relay 2V, wire I23, front contact I42 of relay CD, jumper I43, wire I39, and winding of relay NC, to

With relay NC picked up, the line circuit is energized for a third impulse which is of a negative polarity, as soon as the impulsing relay EP is dropped away to close the line circuit. After relay EP has again picked up to mark the end of the third impulse, relay 3V is caused to pick up and open the circuit just described for relay NC at back contact 88, to cause that relay to drop away. A circuit is closed for the energization of relay PC by the picking up of relay 3V, if the system has been initiated for the transmission of route end controls, from through a circuit including front contact 83 of relay C,

back contacts 84, 85, 86 and 81 of relays IV, 6V, 5V and 4V respectively, front contact 88 of relay 3V, wire I24, front contact 89 of relay CD, back contact 98 of relay SR, wire I29, and winding of relay PC, to

With relay PC picked up, the line circuit is energized for a fourth impulse which is of negative polarity, as soon as the impulsing relay EP is dropped away to close the line circuit.

If, however, the system has been initiated for the transmission of auxiliary switch controls, a circuit is closed for the energization of relay NC instead of relay PC by the picking up of relay 3V. Such a circuit for relay NC is closed from through a circuit including front contact 83 of relay C, back contacts 84, 85, 86 and 81 of relay 'IV, 6V, 5V and 4V respectively, front contact 88 of relay 3V, wire I24, front contact 89 of relay CD, front contact 98 of relay SR, wire I39, and winding of relay NC, to

With relay NC picked up, the line circuit is energized for a fourth impulse which is of negative polarity, as soon as theimpulsing relay is dropped away to close the line circuit.

Thus, two control station codes are provided for the field station illustrated in detail. One code, composed of the characters selects that field station for .the reception of route end controls, and another code composed of the characters selects that field station for the reception of auxiliary switch controls.

It is easily understood by those familiar with the art from the simple example shown and described, how several control station codes can be selected for each field station to be included in the system, in accordance with the requirements of practice.

The next group of impulses. for defining routes is made up of two parts, the first of which defines the entrance point for'the route, and the second of which defines the exit pointfor the route. Each route end for a field station is provided with a different code, thus if the track layout has four-rute ends, a code of two impulses is. sufficient. If a greater number of route ends is provided, the number of impulses must be increased in order to provide a different code for each route end. The maximum number of different codes available for a particular number of impulses is equal to two raised to the power of the number of impulses;

The'two impulses immediately following the fourth impulses, in this embodiment of the inan entrance point for the route initiated. The two impulses immediately following the sixth impulse in this embodiment of the invention, define the route end which is used as an exit point for the route initiated. In accordance with this embodiment of the invention the following code table is provided which shows the codes used for controlling various devices associated with a particular field station.

Code fable Impulse numbers Control codes Station codes 1 Use.

Entrance exit 10 stop. Not used. Route 10-12. Route 10-13. Not used.

11 stop. Route 1ll2. Route 11-13. Route 12-10. Route 12-11. 12 stop.

Not used. Route 13-10. Route 13-11. Not used.

13 stop.

++++++++++++++++ IlIlIllllllllIll I l 1 1++++| 1 I+I+I+|+I+|+I+l+ In considering an example of the polarities selected for setting up a route between two particular route ends, assume a route to be initiated, as heretofore described, from signal It! to signal I2. With reference to the above code table, code No. 3 is to be transmitted for such a route. The sta- 'tion selection code is transmitted for the first four impulses. The fourth impulse is due to the energization of relay PC through a circuit heretofore described. The picking up of stepping relay 4V at the end of the fourth impulse closes a circuit for energizing relay PC from through a circuit including front contact 83 of relay C, back contacts 84, 85 and 86 of relays IV, 8V and V respectively, front contact 81 of relay 4V, wire I25, front contact 9| of relay CD, back contact 92 of relay I3NR back contact 93 of relay I2NR, back contact 94 of relay IINR, front contact 95 of relay 7 IONR, Wire I29, and winding of relay PC, to

vIINR, front'contact I89 of relay IONR, wire I29,

and winding of relay PC, to

The picking up of stepping relay 8V at the end of the fifth impulse, in setting up a route from signal In to signal I2, causes the droppingaway of relay PC by opening its circuit at back contact 85,, and closes a circuit for energizing relay NC lines.

from (+),through acircuit including front contact 83 of relay- C, back contact 94 of relay IV, front contact 85 of relay 6V, wire I21, front contact I9I of relay CD, back contact I92 of relay ISXR, front contact I93 of relay IZXR, wire I39, and Winding of relay NC, to I 4 The picking up of stepping relay IV at the end of the seventh impulse, in setting up a route from signal I9 to signal I 2, causes-the dropping away of relay PC by opening its Circuit at back contact 89, and closes a circuit for energizing relay PC from through a ci rcuit including front contact 83 of relay C, front contact 94 of relay TV, wire I28, front contact I94 of relay .CD, backcontact I95 of relay I 3XR, front contact I96 of relay I2XR, wire I29, and winding of relay PC, to I If the initiation of a cycle has been,accomplished by the positioning of the auxiliary switch control lever and'the depression of the start button, the picking up of relay S R, determines that the fourth impulse shall be as has been heretofore described. '1'

Assume, for example, the operator to initiate the transmission of a message for the operation of the track switches for crossovers 2ts and Sis as has been heretofore described. jSuch-a message includes codeimpulses as shown in the above code chart for code number 29. Levers 2SML and 3SML are-operated to theirdownward position to cause corresponding positioning'of the contacts shown associated therewith by dotted Relays SR and CD are picked up, and relay NC is energized during the fourth impulse in a-manner heretofore described.

The picking up ofstepping relay. vat the end of the fourth impulse, in considering the above selection of controls, causing the dropping away of relay NC by opening itscircuit at a back contact 81, and causes relay PC to be energized by a circuit closed from through a circuit including front contact 83 of relay C, back contacts 84, 85 andBGof relays IV, 6V and 5V respectively, front contact 87 of relay 4V, wire I 25, front contact 9| of relayCD, back contact 92 of-relay I BNR, back contact 93 of relay I2NR, back contact 94 of relay IINR, back contact 95 ofrelay IIlNR, front contact ..I 9! of relay SR, wire I29, and winding of relay PC, to The picking up of relay PCrcauses the fifth impulse to be(+)'.. '-i

The picking up of stepping relay 5V at the end of the fifth impulse, in considering the above selection of controls, causes relay PC to be energized by a circuit closed from through a circuit including front contact 83 of relayC, back contacts 89 and 95 of relays. EV and 6V respectively,1 front contact 99 of relay 5V, wire I29, front contact 99 of relay CD, back contacts 91, 98, 99 and I99 ,of relays ItNR, IZNR, IINR and IIJNR, respectively, front contact I98 of relay SR, wire I29, and winding of relay PC, to (l). The-picking up of relay PC causes the sixth impulseto be v v i The picking up of stepping relay 6V at the end of the sixth impulse, in considering the above selection of controls, causes the dropping away of relay PC by opening its circuit at back contact 785, and causes relay NC to be energized by a circuit closed from ,"through a circuit including front contact 93 of relay C, back contact 84 of relay IV, front contact 95 of relay 6V, wire I21, front contact I9I of relay CD, back contacts I92,

' I93, I99 and H9 of relays ISXR, IZXR, HXR and I 9XR. respectively, frontcontact III of "relay -front contact 84 of relay IV, Wire I29, front con- "tact' I94 of relay CD, back contact I95, I96, H3 and H4 of relays I9XR, IZXR, HXR' and I923 respectively, front contact I I5 of relay SR, contact H9 of lever 3SML in a downward position, and winding'of relay NC, to The picking up of relay NC causes the eighth and last impulse of the series to be It-is obvious from the above description that the fifth and sixth impulses are only to provide for the stepping, because the particular track layout shown requires only the last two steps for the transmission of controls for crossovers Zts and 313 respectively. It is therefore apparent that a: greater number of switch controls can be transmitted-on one cycle, in accordance with the requirements of practice. That is,

each impulse following the station code can be lused for controlling the track switches for a crossover or a single track switch.

If the operator initiates the transmission of a code for putting a signal to stop by the depression twice of the' button for the route at that signal, the polarity of the impulses for the entire series is selected in the same manner as heretofore described in setting up a route.- The polarity of the fifth and sixth impulses is, however, the same as the polarity of the seventh and eighth impulses respectively. This is true because a different code is assigned to each route end rather than to each entrance or exit point. Thus the picking up of an entrance relay NR and an exit relay XR, as has been described, for thesame route end causes the same code to be selected by each of those relays.

Consider, for example, that the operator has depressed button I9NB twice to cause the picking up of relays I9NR and IIlXR, the message to be transmitted under such conditions is code No. 1 of the above code chart. With relay IIINR picked up, the first six impulses are the same as described for transmission of amessage for setting up a route from signal I9 to signal I2.

The picking up of stepping relay W at the end -of the sixth impulse, in the transmission of a message for putting signal I9 to stop, closes a circuit for energizing-relay PC from through a circuit including front contact 83 of relay C, back contact fl lof relay IV, front contact 89 of relay 6V, wire -I2I, front contact I9! of relay CD, back contacts I02, I93 and H99 of relays IHXR,

IZXR and HXR. respectively, front contact II 9 ,of relay IOXR', wire I29, and winding of relay 'PC, to the seventh impulse to be The picking up of relay PC causes The picking up of stepping relay IV at the end of the seventh impulse, in transmitting a message for putting signal I9 to stop, closes a circuit for energizing relay PC from through a circuit including front contact '93 of relay C, front contact 84 of relay IV, wire I23, front contact I94 of relay CD, back contacts I95, I96 and H3 of relays I32GR, IZXR. and IIXR respectively, front contact H4 of relay IOXR, and winding of relay PC, to

It is of course to be understood, as is explained in detail later, that the transmission of a message for putting a signal to stop also restores the parts of the self-selecting network associated with that of operation, such operation is to be considered as typical for other similar specific conditions relative to the setting up of other routes, relative to the auxiliary operation of track switches to other positions, and relative to the restoration of other signals to stop.

Stepping and I mpulsing at the Control Ojfice.- As has been heretofore pointed out, the stepping and impulsing is accomplished in the same manner as the stepping and impulsing shown in the Judge et a1. Patent No. 2,082,544, dated June 1, 1937, to which reference can be made for details of the circuits.

Assuming relay PC to be picked up at the beginning of a control cycle, as is effected when controls are to be transmitted to the field station illustrated in this disclosure, the line circuit is energized from the positive terminal of the battery CB (see Fig. 2) through a circuit including back contact I44 of relay NC, front contact I45 of relay PC, back contact I46 of relay EP, Winding of relay F, line wire 20, winding of relay F (see Fig. 3), a line relay for each of the other field stations included in the line circuit, return line wire 2|, front contact I4'I of relay PC (see Fig. 2), and'back contact I48 of relay NC to the negative terminal of battery CB.

Whenever relay NC is picked up at the beginning of a control cycle, in accordance with a station selecting code requiring its energization, the line circuit is energized from the negative terminal of battery CB, through a circuit including front contact I48 of relay NC, back contact I45 of relay PC, back contact I46 of relay EP, winding of relay F, line wire 20, Winding of relay F (see Fig. 3), a line relay at each of the other field stations included in the line circuit, return line wire 2|, back contact I41 of relay PC, and front contact I44 of relay NC, to the positive terminal of battery CB.

The energization of control line wire 20 from either the positive or the negative terminal of battery CB, causes polar contact 316 of relay F to close an obvious circuit to cause the picking up of the repeater relay FP, which in turn effects the picking up of relay 2FP. These relays are all quick acting relays and are positioned in response to each change in the condition of the line circuit. The picking up of relay 2FP closes an obvious circuit for the energization of relay SA, which in turn closes a circuit for the energization of relay 25A. Relays SA and 28A are maintained picked up throughout a cycle of operation due to their slow acting characteristics in combination with the intermittent energization of relay SA when relay 2FP is picked up.

The picking up of relay SA during the conditioning period at the start of a cycle of operation, closes a circuit for the energization of relay VP from ,through a circuit including front contact I49 of relay SA, front contact I50 ofrelay 2FP, back contact I 5| of relay IV, and winding of relay VP, to The picking up of relay VP closes a stick circuit for maintaining that relay energized during the dropping away of relay 2FP at the end of the first impulse, from through a circuit including front contact I49 of relay SA, front contact I52 of relay VP, back contact I5I of relay IV, and winding of relay VP, to

The dropping away of relay ZFP, at the beginning of the first period of deenergization of the line circuit, closes a second stick circuit for relay VP, from through a circuit including front contact I49 of relay SA, back contact I50 of relay 2FP, front contact I53 of relay VP, and winding of relay VP, to

The first of the above described stick circuits for relay VPis opened at back contact I5I of relay IV when relay IV is picked up during the first period of deenergization of the line circuit, but relay VP is maintained picked up by the second of the above described stick circuits until relay 2FP is picked up to open back contact I50 during the second period of energization of the line circuit.

The picking up of relay 23A during the first period of energization of the line circuit closes a circuit for the energization of relay E from through a circuit including front contact I54 of relay 28A, front contact I55 of relay VP, back contact I56 of relay IV, and upper winding of relay E, to The picking up of relay E closes an obvious circuit for its repeater relay at front contact I51, and the picking up of that repeater relay'EP opens the line circuit at back contact I46 to mark the end of the first. in the series of impulses.

The dropping away of relays FP and ZF'P, as a result of the deenergization of the line circuit, closes a circuit for the energization of the first of the stepping relays, IV, from through a circuit including front contact I58 of relay SA,

.back contact I59 of relay 2FP, front contact I60 of relay VP, back contact I6I of relay 2V, and winding of relay IV, to A stick circuit is closed for relay IV, upon the picking up of that relay, from through a circuit including front contact I58 of relay SA, front contact I62 of relay IV, and winding of relay IV, to That stick circuit maintains relay IV picked up throughout the series of impulses. The pickingup of relay IV opens the above described circu'itfor the energization of relay E at back contact I56 to cause relay E and its repeater relay EP to drop away and again close the line circuit at front contact I46 to effect the energization of the line circuit during a second period, in accordance with the picked up position of either of the relays NC or PC, depending upon the selected polarity for that impulse.

The picking up of relay ZFP as a result of such energization of the line circuit causes the dropping away of relay VP by the'opening of the only circuit for that relay which remains energized, at back contact I50, thus causing relay VP to drop away and remain in a dropped away position until the next period of energizationof the line circuit, at which time it is energized by a pick up circuit closed from through a circuit including front contact I49 of relay SA, front contact I50 of relay ZFP, back contact I63 of relay 3V, front contact I64 of relay 2V, and winding of relay VP, to

The dropping away of relay VP during the second period of energization of the line circuit closes acircuit for the energization of the lower winding of relay E, from through a circuit including front contact I54 of relay ZSA, back contact I55 of relay VP, back contact I65 of relay 2V, front contact I66 of relay IV, and lower winding of relay E, to The picking up of relay E causes the picking up of its repeater relay EP to open the line circuit at back contact I46 and mark theend of the second im- 

